EP 1 507 116 A1 describes a cooling channel for example with baffle-plate cooling and also coolant flowing into the combustion chamber. The heat-shield arrangement shown surrounds the combustion chamber and comprises a plurality of heat-shield elements arranged next to each other on a support structure while leaving a gap. An internal space is formed between the heat-shield elements and the support structure, into which internal space the coolant can flow inward to cool the heat-shield elements. The coolant flows into the internal space through several inlet channels provided in the support structure, with a coolant outlet channel being provided for the controlled exit of coolant from the internal space, which coolant outlet channel opens into said gap.
In order to prevent any blowing out of coolant into the combustion chamber, more complex systems with cooling fluid recirculation are known in which the cooling fluid is conveyed in a closed circuit. Closed cooling schemes with cooling fluid recirculation of this type are described, for example, in WO 98/13645 A1, DE 297 14 742 U1, EP 1 005 620 B1, and EP 1 628 076 A1, and also in EP 0 928 396 B1.
The latter relates to a heat-shield component for a hot gas wall requiring cooling having cooling fluid recirculation and an inlet channel and an outlet channel for the cooling fluid. The inlet channel is directed toward the hot gas wall and expands in the direction of the hot gas wall. The inlet channel, the outlet channel, and the closed hot gas wall bring about complete cooling fluid recirculation so that no losses of cooling fluid whatsoever are incurred due to conveying the coolant.
EP 1 628 076 A1 describes a cooling channel with concave depressions for improved cooling, the concave depressions only being arranged outside the boundary zone on the hot gas wall, while the boundary zones remain free or are provided with turbulators. So-called dimples are arranged there for particularly effective cooling. This achieves the result that the cooling fluid is guided in the direction of the boundary zones and these are therefore cooled more. The arrangement in EP 1 628 076 A1 therefore improves the cooling of the boundary regions by the installation of turbulators. But here also, a high pressure loss is created upon the entry of the coolant into the cooling channel.